Spintronic logic represents an improvement over complementary metal-oxide-semiconductors (CMOS) logic, memory and analog applications because of its low power consumption. A spintronic device includes a dominant magnet that injects a net spin into an output current forcing output electrons to align their spins. Aligning the spin of electrons in the output results in an excess of spin up or spin down electrons.
FIG. 1A illustrates an example branch 100 of a generic circuit including two nodes 110, 115 connected by a scalar conduction element 120. In the example branch 100 of FIG. 1A, a scalar current 130 passes along the conduction element 120 between nodes 110, 115, sending electrons 140 flowing along the conduction element 120 between nodes 110, 115.
FIG. 1B illustrates an example circuit branch 150 including nodes 160, 165 connected by a spin conductance element 170 in a spin circuit. In the example of FIG. 1B, a vector spin current 180 in the branch 150 of a spin circuit is the net vector flow of electrons 190 associated with a magnetic moment between the nodes 160, 165. The vector spin current 180 is represented by a three dimensional tensor described by a direction of the flow of the charges constituting the spin current 180 and a direction of the net magnetic moment (spin) of the charges along each Cartesian coordinate axis (x, y, z). The total spin current vector is a combination of the charge current and vector spin current in a vector (e.g., a 4×1 vector, etc.) for example. The electrons 190 associated with the spin current 180 have a spin or polarization including one or more of an x, y, or z component.
A vector spin voltage is a state variable associated with an accumulation of spins of a certain direction. The spin voltage is proportional to a net spin population. For example, the total spin voltage vector is a combination of a scalar columbic potential and a vector spin potential in a vector (e.g., a 4×1 vector, etc.).
A spin conductance relates vector spin voltages to vector spin currents. The spin conductance can be represented by a spin conductance matrix. The spin conductance matrix of a conductance element is a matrix proportionality constant relating the vector spin current though an element with the vector spin voltage difference applied across the conductance element 170. For example, the spin conductance matrix can be represented as a 4×4 vector that scales and reorients the voltage vectors to obtain the spin current vector. The sixteen components of the example spin conduction matrix are non-zero and are set by the magnetic and geometric properties of the spin conductance element, for example.
However, current spintronic logic suffers from a lack of control and variability that reduce the utility of such logic to only basic operation.
The figures are not to scale. Instead, to clarify multiple layers and regions, the thickness of the layers may be enlarged in the drawings. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used in this patent, stating that any part (e.g., a layer, film, area, or plate) is in any way positioned on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, means that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. Stating that any part is in contact with another part means that there is no intermediate part between the two parts.